Conventional armature windings that are constituted by distributed windings are configured by arranging hexagonal winding bodies at a pitch of one slot in a circumferential direction, the armature windings being configured by winding a conductor wire into pairs of slots that are positioned on two sides of a plurality of circumferentially consecutive teeth. Thus, electric potential differences among conductor wires within identical phases are small, but large electric potential differences act between the conductor wires in different phases. Electric potential differences that are close to a power supply voltage may act between conductor wires in different phases, particularly if the conductor wire of another phase is close to an electric power supplying portion. Thus, partial discharges are more likely to occur if used at high voltages.
In consideration of such conditions, conventional rotary electric machines have been proposed that achieve size reductions as well as high voltage and high output by using different thicknesses or insulating materials in insulating layers in slot portions and in coil end portions to suppress the occurrence of partial discharge in the coil end portions (see Patent Literature 1, for example).